The present invention relates to a pneumatic tire having a sidewall portion provided in the outer surface thereof with a serrated area.
In a tire manufacturing method in which a carcass ply strip is wound around a tire drum or former, usually the circumferential ends or edges of such carcass ply strip are overlap jointed. Thus, such an overlap joint extends from the bead to bead through the tread portion and sidewall portions. Therefore, when the tire is vulcanized, due to a high pressure applied to the inside of the tire, there is a possibility that the overlap joint forms a radially extending bulge or dent in the outer surface of the sidewall portion.
In order to make such unwanted bulge/dent unnoticeable, there has been utilized a serrated area (b) formed in the outer surface of the sidewall portion shown in FIG. 8.
The conventional serrated area (b) is formed by radial ridges (a) extending in parallel with radial directions of the tire (patent document 1) or oblique ridges inclined with respect to radial directions at a constant angle (patent document 2).                [patent document 1] Japanese Patent Application Publication No. 2009-143488        [patent document 2] Japanese Patent Application Publication No. 2003-182317In such a conventional serrated area (b), the serration pattern becomes monotonous or uniform. This is helpful for increasing the visibility of marks (shown in FIG. 8 as white circles) provided in the serrated area (b). But, there is a possibility to rather emphasis the appearance of the bulge/dent, in particular when the sidewall rubber thickness is small.        